This invention relates to seal ring systems for fluid actuators and, more particularly, to seal ring systems of a composite design.
In recent times, the conventional O rings and chevron type packings employed in fluid actuators have been replaced by multiple element sealing arrangements including elements formed of both pressure deformable and non-deformable materials. While these multiple element sealing systems offer improvements over the O ring and chevron type seals, particularly in high pressure applications they do possess certain disadvantages. For example, in some known constructions, the deformable component, such as a rubber ring, is relied upon to perform some sealing and in contacting the other part is subject to wear. Often, metal rings, which do have a significantly long wear life, are used as the non-deformable components. However, they are susceptible to galling when performing the sealing function. In those systems in which split rings are utilized, fluid leakage or bypass often occurs through the ring partings at high pressures. One attempt to overcome these disadvantages is disclosed in U.S. Pat. No. 3,612,538, on a multiple element Piston Ring System, granted on Oct. 12, 1971 and assigned to the same assignee as the present invention. The present invention constitutes a further improvement in such a multiple element seal ring system and is directed to a construction positively preventing permanent deformation of the deformable expander ring.